Not Applicable
Not Applicable
Not Applicable
The invention relates to a multifunction switch to be mounted on the steering wheel of an automobile, comprising an oblong housing with a contact assembly accommodating circuit elements, comprising at least one automatically restoring button with a member acting on the circuit elements, and comprising an actuating ridge with two opposing actuating faces.
An electric pushbutton switch of this type is known from DE 195 11 878 A1; it is equipped with a housing accommodating circuit elements and several automatically restoring and eccentrically mounted pushbuttons, each having a stud which acts upon the circuit elements. Each pushbutton features an actuating ridge with two opposing actuating faces, said ridge being aligned approximately axially parallel with the pushbutton mount. The actuating force introduced on the side of the pushbutton mount generally parallel with the housing has the same working direction upon the pushbutton as the actuating force introduced on the opposite side generally perpendicularly to the housing. Two diametrically opposed pushbutton switches are normally joined to the steering wheel disk of an automobile, by means of mounting flanges molded to the housing ends, such that the actuating faces of the pushbuttons protrude through an aperture between the steering wheel rim and the steering wheel disk. Such electric pushbutton switches arc suited particularly to trigger switching functions, for example, for temporary speed control (Tempomat) of the automobile and/or to control operating functions of a radio-cassette unit available in the vehicle. Accommodated in the pushbutton switch housing is a printed circuit board configured as a contact assembly, with which a spring unit mounted on the housing is coordinated. Actuation of a pushbutton causes the pertaining stud to act on the spring unit and close or interrupt current paths on the printed circuit board. The latter is mounted rigidly in the housing interior. Such printed circuit boards are frequently provided with circuit elements, preferably microswitches which trigger switching and operating functions. A considerable disadvantage of the pushbutton switches is constituted by the eccentric mounting of the pushbuttons on the housing and by the disuniform design of the housing, since the one pushbutton switch is intended for left-side mounting and the other for right-side mounting on the steering wheel disk. Accordingly, the outer contour of the housing is between the steering wheel rim and the steering wheel disk adapted to this area of the aperture. Suited for that purpose is an eccentric mounting of the pushbuttons on the housing. As a result, however, the pushbutton switch can be mounted only on that side of the steering wheel disk which is intended therefor, making it necessary to fabricate for one steering wheel type two pushbutton switches of different design. This separate fabrication results in relatively high costs.
The objective underlying the invention is to create a multifunction pushbutton switch of the initially named type which allows inexpensive fabrication and variable use on the steering wheel of an automobile.
This objective is satisfied according to the invention in that
the pushbutton is mounted in toggle fashion, centered on the housing, and has a cross section which transverse to its mounting axis is symmetric, the mounting axis extending parallel to the actuating ridge, and
the housing is symmetric in its longitudinal section and its cross section and possesses on one of its long sides, or centered on its underside, a mounting tab which extends generally radially to the steering column of the automobile.
The housing cross section is generally symmetric on all sides and allows, in contingence on assembly conditions and application, a rotation of the multifunction pushbutton switch about a vertical axis perpendicular to its longitudinal axis, prior to its installation on one side of the steering wheel disk of an automobile, with the mounting tab which extends radially being fitted centrally on the underside of the housing. This enables the assembly of the multifunction pushbutton switch bath in the one installation position and also in another installation position rotated 180xc2x0 about the vertical axis of the switch. Owing to the symmetric longitudinal section of the housing, the multifunction pushbutton switch can be pivoted about its longitudinal axis or transverse axis and assembled to the one or the other side of the steering wheel disk, with the assembly variant described above being available additionally, due to the switch rotation by 180xc2x0 about the vertical axis. If the multifunction pushbutton switch is intended only for installation on one or the other side of the steering wheel, with the switch then being turned about its transverse axis, the mounting tab is provided only on one long side of the housing. Preferably, the mounting tab is arranged centrally on the underside of the housing, which permits all rotary or pivotal movements of the multifunction pushbutton switch.
The cross-sectionally symmetric design of the pushbuttons suited for mounting on the housing allows their selective slip-on or replacement under allowance for, or in contingence upon, the installation position of the multifunction pushbutton switch and the icons showing on the buttons to symbolize the switching functions to be controlled. As a result, a single multifunction pushbutton switch may be fabricated which can be installed in any position and on any side of the steering wheel disk of an automobile. The need for fabrication of a pushbutton switch, separate for each side of the steering wheel disk, is thus eliminated and reduces production costs.
Alternatively, the objective also is satisfied by
mounting the pushbutton in toggle fashion, centered on the housing, and having a cross section that is in symmetry with its mounting axis, with the mounting axis extending parallel to the actuating ridge, and
by giving the housing, in longitudinal section, an asymmetric design with a mounting tab centered on its underside and extending generally radially relative to the steering column of the automobile.
The asymmetric design of the present multifunction pushbutton switch allows, in longitudinal section, a variable installation, notably due to the different curvature of the housing ends adapted to the aperture between the steering wheel rim and the steering wheel disk, for example, when the steering wheel shape has an irregular contour. Owing to the central arrangement of the mounting tab on the underside of the housing, the latter may be turned about its longitudinal axis and installed both on the one and also the other side of the steering wheel disk. The symmetrically configured pushbuttons allow a variable arrangement as needed, on the housing of the multifunction pushbutton switch.
According to an improvement of the invention, the housing features mutually spaced brackets which are arranged crosswise to its longitudinal axis and on which opposing and centered mounting pins and mounting holes are respectively provided. To enable a pushbutton to mesh with the pertaining brackets of the housing, the pushbutton possesses side flanges which are arranged crosswise to its bracket axis and possess respectively a mounting hole or mounting pin. A two-sided toggle movement of the pushbutton is achieved about the mounting axis, and which is limited only by the pushbutton rims opposing the actuating ridge.
Multifunction pushbutton switches and their central components are generally injection-molded of plastic. The brackets are suitably configured integral with the housing, the side flanges of the pushbutton integral as well, in order to lower the manufacturing expense and production costs.
Injection-molding of plastic allows providing functional elements easily on the relevant components, which elements need not be manufactured separately. Therefore, according to a further embodiment of the invention, a switching element is molded to the inside of each actuating face of the pushbutton, and the switching element extends essentially vertically to the coordinated circuit element on the contact assembly.
A further preferred provision is spring-loading the pushbutton against the housing. To that end, a stud is molded to the inside of the actuating ridge of the pushbutton. A sleeve is formed on the base of the housing, which accommodates a spring-loaded follower pin and is directed at the actuating ridge of the pushbutton, with the follower pin bearing on a cam. The spring-loaded follower pin aids the toggle movement and resetting of the pushbutton relative to the housing.
According to an improvement of the inventional solution, the contact assembly is detachably retained on the housing base by means of clamping elements formed on the housing. The contact assembly is thus positionally secured in the housing. But the detachable clamping enables also a 180xc2x0 rotation of the contact assembly containing the circuit elements, so that the latter are located either on the one or the other long side of the housing. Depending on the installation position of the multifunction pushbutton switch, the contact assembly can thus be fitted in the respective position in the housing and fastened there.
The contact assembly is preferably configured as a printed circuit board, its circuit elements being microswitches, bridges or the like. Microswitches have been found to be particularly suitable, due to their high operational fitness and easy and inexpensive manufacture.
In a favorable embodiment of the invention, the pushbutton switch is mounted in the area of the steering wheel of an automobile, such that a driver""s hand gripping the steering wheel rim can engage with the thumb the one actuating face of the pushbutton and with the fingers the other actuating face, the hand finding support on the steering wheel rim. Hence, the required actuating force is very easily controlled. The actuating force is introduced in keeping with the natural thumb or finger movement, and the grip around the steering wheel rim need not be released in actuating the multifunction pushbutton switch.
To allow for the physical particulars and for the alignment of the thumb and finger joints, the multifunction pushbutton switch is according to a favorable improvement coordinated with the steering wheel rim such that the actuating ridge of the pushbutton extends behind the steering wheel rim approximately parallel with it and set back. This provides an optimum coordination of the pushbutton with the fingers and the thumb.
In a further embodiment, the housing is joined to the steering wheel by means of a mounting tab, with the actuating faces of the pushbutton protruding through an aperture in a steering wheel disk surrounding the steering wheel hub and with no steering wheel spokes provided in the area of the pushbutton. As the steering wheel is turned, the pushbutton follows along at the same angle. Pushbutton actuation is possible also in critical situations, without taking one""s hand off the steering wheel. Furthermore, an unobstructed view of the pushbutton is always assured.
Moreover, the actuating face of the pushbutton near the operator features preferably at least one transparent or opaque icon surface illuminated by an illuminating element arranged beneath the pushbutton. Especially at night and also in a phase when an operator is getting accustomed to a pushbutton combination, the display and illumination of the icon surface for the switching function precludes erroneous operation. By turning or replacing it, the pushbutton can be used at the spot of the multifunction pushbutton switch where the relevant switching function is provided for on the contact assembly, corresponding to the icon on the pushbutton""s icon surface. An icon surface may be provided, also on any actuating face of the pushbutton, in order to further enhance the usage variations of the pushbutton.
In order to direct the fall light intensity at the icon surface of the pushbutton and to shield its surroundings from the light effect, a light guide which eliminates scatter light extends from the housing base perpendicularly to the icon surface on the actuating face of the pushbutton.
The pushbutton switch mounted on the steering wheel also suitably comprises at least three adjacent pushbuttons, thus allowing several switching functions on a single electric pushbutton switch. The center or outer pushbuttons feature in this case, on their side flanges facing one another, sealing collars which bridge the clearance between adjacent pushbuttons. The sealing collars prevent dirt from penetrating the electric pushbutton switch. Furthermore, the unintended radiation of light given off by the illuminating element contained in the housing is prevented.
To be able to utilize the space available on the steering wheel rim, especially between two steering wheel spokes, and to realize many switching functions, preferably two diametrically opposed pushbutton switches are arranged in the area of the steering wheel. Different switching functions may thus be assigned to the buttons of each pushbutton switch and to the circuit elements of the contact assembly. Thus it is possible to assign to the buttons of each pushbutton switch and to the circuit elements of the contact assembly switching functions for controlling the road-holding properties of the automobile or for controlling a radio and/or tape player and/or CD player and/or CD changer installed in the automobile.